Web Server Application Logs LTEC2013

Poor Man's Digital Forensics

Michal ŠpačekLead Web Developer

Slevomat.cz

www.michalspacek.cz @spazef0rze


Web Developers

http://example.com/products

I'm a web developer. I've been a web developer since, like, 2000. Web developers, you know, build web applications and web applications run on the Internet and are using addresses just like this one above.


So Web Developers

http://example.com/product?id=123

The better of us they also build web applications with addresses looking like this one. Such web application displays a lot of useful details about a product or whatever info the developer of the application wants it to

display.


Wow, Web Developers

http://example.com/product?id='+UNION+SELECT+1,2,3,4+#

SQL Injection Attack

The best of us, web developers, they build applications which display a lot of useful details and also whatever the bad guy wants the application to display. This is called the SQL Injection Attack and it is responsible for some major information leaks in last few years and is caused by the developer not properly handling user

input. It is pretty common, unfortunately.


Many Web Developers

http://example.com/products

http://example.com/product?id=123

http://example.com/product?id='+UNION+SELECT+1,2,3,4+#

So we are web developers, building web applications. The applications are different, of course, but there's one thing making them all the same, at least from one particular point of view. The applications are viewed

from web browsers making requests to web servers. And guess what…


All the Internet

WEB SERVERS

are writing access

L O G S !

Yes! Exactly. Whenever there's a request coming from a browser no matter what information ends up being sent back to it, the requested address is written down to the server access log. So later you can see what

your users are looking for, if needed.


All the Internet

YOUR WEB APPLICATION

should be writing application

L O G S !

Just like the web server your application can also write logfiles. These files should contain more information and debugging data because your application knows much more about the request than the server. It knows

a lot about a user making the request, what they want to buy and what was the result of charging their payment instrument.


Many Logs

● Disk s p a c e

● Logger performance

● Somebody has to read logs

Of course, logging is not easy. It's hard because logs take space and once your log files are too big there's no more room for other data on the server and the server stops serving requests. The server has to perform well

because it simply has more things to do. Your hard drives need to perform well too. And the hardest part about logging is that somebody has to read the logs.


Be a Digital Forensics Guy

Search the logs for

SELECT

BUT! If you have logs you can be a digital forensics guy, too! No, not the pro one, but good enough to detect a breach or data leak. Just search the logs for some keywords and while you may get some false positives, you may also spot something. Remember the SQL Injection Attack example? But please, don't modify the logs, the

pros need them in their original state.


Michal Špaček says

Write logs

Read logs

Before it's too late

Here's my advice. Write the logs. Read them as well. A lot of companies don't know they had their data leaked until they read it on TechCrunch or Slashdot. That is well too late. Do something so that you're the

first one to know that something went wrong. The second one, actually. The first one is always the guy making it away with your data.

Technology

Web Server Application Logs LTEC2013